Phosphonic-acid grafted hybrid inorganic-organic proton electrolyte membranes (PEMs)

Abstract

A proton conducting polymer is formed by the copolymerization of a plurality of compounds, including a silicon compound comprising an organic chain, and a compound including at least one acid group. The polymer comprises a hybrid organic-inorganic matrix having acid groups linked through a linking group. The linking group may include one or more electron withdrawing groups. The electron withdrawing group may be a halogen.

1. A copolymer comprising the reaction product of a plurality of silicon compounds, each silicon compound including at least one silicon atom, the silicon compounds including:
 a first silicon compound including an organic chain, the organic chain having at least two carbon atoms; and 
 a second silicon compound including at least one acid group, the acid group being linked to a silicon atom of the second silicon compound through a linking group, 
 wherein the linking group includes an electron withdrawing group, so as to enhance the acidity of the acid group. 
 
     
     
       2. The copolymer of  claim 1 , wherein the acid group is a phosphonic acid group. 
     
     
       3. The copolymer of  claim 2 , wherein the linking group comprises an alkyl chain. 
     
     
       4. The copolymer of  claim 3 , wherein the alkyl chain is at least partially fluorinated. 
     
     
       5. The copolymer of  claim 1 , the organic chain having a first end and a second end, the first end being connected to a first silyl group, the second end being connected to a second silyl group. 
     
     
       6. The copolymer of  claim 5 , wherein the organic chain is a polypropylene oxide chain. 
     
     
       7. The copolymer of  claim 5 , wherein the organic chain is a hydrocarbon chain including at least two carbon atoms. 
     
     
       8. The copolymer of  claim 1 , wherein the plurality of silicon compounds includes a third silicon compound,
 the third silicon compound being a silane derivative having at least one hydrolysable group. 
 
     
     
       9. The copolymer of  claim 8 , wherein the third silicon compound is an alkoxysilane. 
     
     
       10. The copolymer composition of  claim 8 , wherein the third silicon compound is tetraethoxysilane. 
     
     
       11. A polymer electrolyte membrane including the copolymer of  claim 1 . 
     
     
       12. A fuel cell including the polymer electrolyte membrane of  claim 11 . 
     
     
       13. A copolymer, comprising
 a three-dimensional organic-inorganic hybrid matrix, including silicon atoms, oxygen atoms, and an organic chain; and 
 an acid group chemically linked to the organic-inorganic hybrid matrix by a linking group, 
 wherein the linking group further includes an electron-withdrawing group. 
 
     
     
       14. The copolymer of  claim 13 , wherein the electron-withdrawing group includes a halogen atom. 
     
     
       15. The copolymer of  claim 13 , wherein the linking group includes two or more carbon atoms. 
     
     
       16. The copolymer of  claim 15 , wherein at least one carbon atom within the linking group is halogenated. 
     
     
       17. The copolymer of  claim 15 , wherein at least one carbon atom within the linking group is fluorinated. 
     
     
       18. The copolymer of  claim 13 ,
 the acid group being a phosphonic acid group, 
 wherein the phosphorus atom of the phosphonic acid group is bound to a carbon atom of the linking group, the carbon atom of the linking group being fluorinated. 
 
     
     
       19. The copolymer of  claim 13 , the copolymer being formed from a plurality of precursors including a first precursor, the first precursor including the organic chain. 
     
     
       20. The copolymer of  claim 19 , wherein the organic chain of the first precursor has a first end and a second end, the first end being attached to a first silicon-containing group and the second end being attached to a second silicon-containing group. 
     
     
       21. The copolymer of  claim 20 , wherein the first silicon-containing group and the second silicon-containing group are both hydrolyzable silane derivatives, the copolymer being formed by a process including at least partial hydrolysis of both the first silicon-containing group and the second silicon-containing group. 
     
     
       22. The copolymer of  claim 20 , wherein the first silicon-containing group and the second silicon-containing group are both alkoxysilyl groups. 
     
     
       23. The copolymer of  claim 20 , wherein the organic chain is poly(propylene oxide) or a derivative thereof. 
     
     
       24. The copolymer of  claim 20 , wherein the plurality of precursors includes a second precursor, the second precursor including the acid group. 
     
     
       25. The copolymer of  claim 24 , wherein the second precursor includes a second precursor silicon-containing group, the linking group, and the acid group,
 the copolymer being formed by a process including at least partial hydrolysis of the second precursor silicon-containing group. 
 
     
     
       26. The copolymer of  claim 24 , wherein the second precursor includes the acid group and a first functional group, the first functional group reacting with a second functional group so as to attach the acid group to the hybrid inorganic-organic matrix through a flexible linking group. 
     
     
       27. The copolymer of  claim 26 , wherein the second functional group is part of a third precursor, the third precursor including a third precursor silicon-containing group,
 the copolymer being formed by a process including at least partial hydrolysis of the third precursor silicon-containing group. 
 
     
     
       28. The copolymer of  claim 24 , wherein the first and second functional groups are both vinyl groups. 
     
     
       29. A polymer electrolyte membrane including the copolymer of  claim 13 . 
     
     
       30. A fuel cell including the polymer electrolyte membrane of  claim 29 . 
     
     
       31. A method of fabricating polymer electrolyte membrane, the method comprising:
 providing a first precursor including an organic chain having at least two carbon atoms, the organic chain having a first end and a second end, the first end being attached to a first hydrolyzable silicon-containing group, the second end being attached to a second hydrolyzable silicon-containing group, the organic chain including a polypropylene oxide chain: 
 providing a second precursor, the precursor including an acid group and a first functional group; 
 forming a copolymer by copolymerizing at least the precursor and the second precursor, the copolymerization including hydrolysis of the first and second hydrolyzable silicon-containing groups, 
 so as to produce a hybrid inorganic-organic matrix including silicon atoms and the organic chain, the acid group being linked to the hybrid inorganic-organic matrix by a linking group; and 
 fabricating the polymer electrolyte membrane using the hybrid inorganic-organic matrix. 
 
     
     
       32. The method or  claim 31 , wherein the acid group is a phosphorus-containing acid group. 
     
     
       33. The method of  claim 31 , wherein the acid group is a phosphonic acid group. 
     
     
       34. The method of  claim 31 , wherein the second precursor includes the linking group, the first functional group being a third hydrolyzable silicon-containing group connected to the acid group through the linking group. 
     
     
       35. The method of  claim 34 , wherein the linking group is a partially fluorinated aliphatic hydrocarbon chain having 2 to 18 carbon atoms. 
     
     
       36. The method of  claim 31 , further including provision of a third precursor,
 the third precursor including a including a fourth hydrolyzable silicon-containing group and a second functional group, 
 copolymerization including hydrolysis of the first, second, and fourth hydrolyzable silicon-containing groups, 
 copolymerization further including a reaction of the first and second functional groups, wherein the acid group is connected to the hybrid inorganic-organic matrix. 
 
     
     
       37. The method of  claim 36 , wherein the first and second functional groups are both vinyl groups. 
     
     
       38. A copolymer formed by the copolymerization of at least:
 a first silicon compound including an organic chain; 
 a second silicon compound including a first functional group; and 
 a third compound including a second functional group and an acid group, 
 the copolymerization including at least partial hydrolysis of silicon-containing groups within the the first and second silicon compounds so as to form an inorganic-organic hybrid matrix containing silicon atoms, oxygen atoms, and the organic chain, 
 the copolymerization further including reaction of the first and second functional groups so as to attach the acid group to the inorganic-organic hybrid matrix, 
 wherein the acid group is bound to the inorganic-organic hybrid matrix through a linking group, the linking group being an aliphatic hydrocarbon group having 2 to 18 carbons, 
 the linking group including an electron withdrawing group. 
 
     
     
       39. The copolymer of  claim 38 , wherein the electron withdrawing group includes a fluorine atom. 
     
     
       40. A polymer comprising a hybrid inorganic-organic matrix having at least one backbone unit of the form —O—Si(A,B)—R—Si(C,D)—,
 wherein A,B,C,D each represent substituent groups, and R represents an organic chain including at least 2 carbon atoms, 
 at least one substituent group including a linking group and a phosphonic acid group, the linking group connecting the phosphonic add group to a silicon atom, 
 the linking group including at least 2 carbon atoms, 
 the linking group including an electron withdrawing group. 
 
     
     
       41. The polymer of  claim 40 , wherein
 the electron withdrawing group is a C—F group. 
 
     
     
       42. A composite of a first polymer with a basic polymer, wherein the first polymer comprises a hybrid inorganic-organic matrix having at least one backbone unit of the form —O—Si(A,B)—R—Si(C,D)—
 wherein A,B,C,D each represent substituent groups, and R represents an organic chain including at least 2 carbon atoms, 
 at least one substituent group including a linking group and a phosphonic acid group, the linking group connecting the phosphonic acid group to a silicon atom, 
 the linking group including at least 2 carbon atoms. 
 
     
     
       43. The composite or  claim 42 , wherein the basic polymer is selected from a group consisting of polybenzimidazole, poly(silamine), poly(ethylene imine), poly(2,5-benzimidazole), poly(decamethylene carboxamide), poly(bis(trifluoroethoxy)phosphazene), polyurethane, polyacryamide, and derivatives thereof. 
     
     
       44. An ion electrolyte comprising the polymer of  claim 40 .